Abstract We consider physical foundations for the realization of high-modulus and high-strength polymer/carbon nanotube nanocomposites with mechanical characteristics comparable with those for steel. We have determined two main factors that make it possible to obtain such nanocomposites, i.e., the structure of the nanofiller in the polymer matrix and a quite high concentration of the nanofiller. The

Abstract The heat transfer in a contact–film–substrate system was analyzed under conditions in which the heat removal from a sample to the substrate is insufficient to avoid overheating of the sample. A method for increasing the heat removal from thin-film samples is proposed for low temperatures, when a high-density electric current passes through them. The property of an anomalously high thermal

Abstract Dynamic brittle fracture under high-rate loading conditions is analyzed. A new numerical algorithm based on peridynamic approach and structural–temporal model of fracture is used to predict the start of a crack in glassy polymer samples. The results of calculations are compared with available experimental data.

Abstract Flows of ions with energies on the order of megaelectronvolts, which propagate both in the axial direction and in the direction perpendicular to the symmetry axis of the discharge, are recorded in a high-current low inductance vacuum spark. Estimates based on the measurements of the total charge of suprathermal electrons emitted from the region of the waist of the current channel in the axial

Abstract A radio-technical scheme of a hierarchical thalamocortical brain network with an external input is developed. Various regimes of induced and self-oscillations (including hard-excitation regime) are revealed in the study of the proposed model. Parameters at which the scheme exhibits activity similar to spike-wave discharges of absence epilepsy are determined, which proves the hypothesis in

Abstract The influence of Brownian motion–induced deposition and coagulation of particles on the parameters of nanoaerosols flowing through a duct has been studied. The problem has been considered in the 2D statement with allowance for a nonuniform velocity profile of the medium across the duct. For equal Knudsen numbers, the concentration and radius distributions of clusters resulting from the particle

Abstract Analysis of the development of deformations under pulsed loading has shown the decisive role of powerful ultrasonic vibrations of a sample in the standing wave mode. The effect of mass transfer of atoms and ultrafine particles of the hardening phase from the matrix material to the spall damage zone on the microstructure of deformation bands is determined. Rapid cooling of the metal inside

Abstract The electrogenic properties of plant–microbial fuel cells (P-MFCs) assembled into a battery are studied. The operation of a single cell is studied experimentally in comparison with parallel and series connections of cells, which are two options for connection in an electrical circuit. A potential difference of ~70 mV, which gradually vanishes, is registered in a P-MFC that does not include

Abstract Using the methods of self-similarity for a laminar free-convective film boiling on a vertical finite-length surface submerged into a large volume of an arbitrarily subcooled liquid, we have derived expressions for the Nusselt criterion with a continuous transition from the film boiling in the saturated liquid to conditions of the strongly subcooled liquid for heat transfer between the heating

Abstract The solution to the problem of the shape of the lateral surface of a vertical 3D catenoidal liquid bridge of small volume between two arbitrary convex solid surfaces in the axisymmetric case taking into account the gravity force is presented. A variational formulation of the initial problem is given. The solution is found by the iteration method under the assumption of a small Bond number

Abstract The mechanical properties of materials based on graphene C62H20 and polyethylene (–CH2–CH2–)n have been studied using the semiempirical PM3 method, and visual models of molecules have been constructed. The calculated values of mechanical parameters show that these materials offer high flexibility and high strength. Orbital energies, ionization potentials, total energies of electrons, strength

Abstract The article presents the results of studying the transfer of heat and particles in the Globus-M2 spherical tokamak in discharges with neutral injection at the current ramp up. An atomic beam was injected into the tokamak plasma at a fixed toroidal magnetic field of 0.7 T. The plasma current on the plateau was varied in the range 0.2–0.3 MA. Based on the electron temperature and concentration

Abstract Generation of ultrawideband electromagnetic radiation by a vacuum photodiode with a plane cesium antimonide photocathode is studied. Thin aluminum plates deposited on a sapphire input window serve as the anode of the photodiode. Electron emission from the photocathode is initiated by the second-harmonic radiation (λ = 385 nm) of a titanium–sapphire laser system with a pulse duration of about

Abstract We report the results of testing the dynamic strength of Al2O3 nanoceramics with different concentrations of five-layer graphene under the action of a high-current nanosecond electron beam and a high-voltage electric discharge of the same nanosecond duration. It is found that, under pulsed loading, an increase in the graphene content in the composite increases the brittleness of the nanocomposite

Abstract An array of ten built-in divertor probes was installed on the lower dome of the Globus-M spherical tokamak. It was used to measure the profiles of the floating potential, electron temperature, ion saturation current, and heat flux density to the divertor. It is demonstrated that there is a sharp change in the floating potentials of the probes located near the outer separatrix leg at the development

Abstract In this paper, we experimentally determine the drag coefficient when conical and cylindrical impactors penetrate into sandy soil. In the experiments, the half-opening angle of the conical tip of the penetrator (indenter) varied from 10° to 90°. The velocity of indenter movement varied in the range of 0.2–2.0 km/s. The average values of the drag coefficient are obtained for conical bodies during

Abstract The structures of carbon nanotubes synthesized by catalytic CVD in the same reactor using different carbon-containing precursors and a FeCl3 catalyst have been compared. Methane and acetylene were applied as carbon-containing precursors. Iron chloride has been applied on silicon substrates by drying a drop of its water solution on the silicon surface. The influence of temperature and pressure

Abstract This paper presents an analytical overview of the study of the kinetic and physicochemical characteristics of composite membrane films. UAM-100, UAM-150, and MGA-95 composite films have been studied using thermogravimetry in the temperature range from 30 to 300°C. A kinetic analysis of experimental data by the Freeman–Carroll method is carried out. It was found that hydrated water for all

Abstract Effect of regimes of fabrication of nanostructured polymer composites filled with carbon nanotubes on electrophysical characteristics is analyzed. Dependence of the conductivity of composites in a frequency interval of 50 Hz–5 MHz and a temperature interval of 15–375 K on the dimensional effect of multi-walled carbon nanotubes, method for functionalization, and method for ultrasonic processing

Abstract Taking damping into account in the problems of structural dynamics is an important and nontrivial problem. Its complexity is primarily determined by the required specification of correct characteristics of the materials used and the choice of a model suitable for analysis. We consider some models of viscoelastic materials as regards the possibility of applying these models in harmonic analysis

An Erratum to this paper has been published: https://doi.org/10.1134/S106378422102016X

Abstract We have analyzed the possibility of improving deformation–force properties of ring-shaped drives made of titanium nickelide and operating in the regime of two-way shape memory effect (TWSME). For this purpose, thermocycling of an oval sample was used with the transformation of the material from the low-temperature martensite phase to the high-temperature austenite phase in free state and cooling

Abstract The initial composition and chemical state of nanopowder primary particles obtained by grinding natural diamond and detonation synthesis have been studied by X-ray photoelectron spectroscopy. It has been shown that the primary particles of both nanopowders contain mainly carbon and oxygen atoms. The signals from nitrogen, sulfur, chlorine, and metal atoms in the photoelectronic spectrum do

Abstract We consider the regularities of a plastic flow in materials with strain-induced phase transformation in titanium nickelide and trip steel as examples. The experimental analysis of plastic deformation processes has been carried out using the technique of digital correction of speckle images, which makes it possible to describe quantitatively the behavior of plasticity fronts associated with

Abstract Generation processes of a photoacoustic response of a layered polyethylene/hydrogel structure by its irradiation with periodically modulated light have been experimentally studied. The heat sources are located in a gel near the interface with polyethylene. The response in the form of the pressure oscillations occurs as a result of the thermoelastic strain of the polyethylene layer by its

Abstract The ideas of pseudogap and nanocrystals have applied to mechanism of electrical conduction in silicate glass doped by oxides of transition metals (thick film resistors). Pseudogap is formed near the valence band of the glass due to diffusion of dopant atoms into the glass in calcination. Nanocrystals are generated in the glass in melting process and undergo structure transitions at high temperatures

Abstract The effect of a high-frequency discharge on the change in the topography of the surface of KU-1 optical quartz and transmission of visible light (400–1000 nm) is studied. The working gases of the discharge are D2 and a D2/N2 mixture, in which the fraction of N2 is 25 mol %. The addition of nitrogen increases the rate of sputtering from 60 to 300 nm/h without changing the stoichiometry of the

Abstract A model of a thermal vacuum system (thermostat) for regulation and stabilization of temperature of the primary mirror of a cooled optical collimator for carrying out tests of optoelectronic equipment operating in the infrared region is designed. An original method for solving the system of nonlinear equations of radiative heat transfer in a thermostat is developed, and the uniformity of the

Abstract The influence of nonconductive disk-shaped inclusions (cracks) on the dc conductivity of a conducting medium has been considered. The functional dependences of an additional relative resistivity of the material on cracking factor (joining ratio) have been found for thin and thick samples. It has been found that the cracking-induced additional relative resistivity of a thick conducting material

Abstract Experiments on the giant magnetoresistance effect observed in microwave reflection have been conducted in the frequency range of 26–38 GHz on (CoFe)/Cu superlattices exhibiting giant magnetoresistance. The amount of the effect has been determined (up to +3% maximum), and its magnetic field dependence has been found. The microwave reflection coefficient versus magnetic field dependence has

Abstract We report on results of investigation into the structure of a plasma jet generated by a coaxial plasma accelerator with conical insert in the discharge formation region. Using high-speed optoelectronic camera, we detected an inhomogeneous structure of glowing fractions of argon and deuterium jets. It was found that the jet radiation intensity oscillates with a characteristic frequency of 0

Abstract Atomic-force microscopy methods were used to study specimens of cathodes of multiwire proportional chambers subjected to a long-term exposure to a β-source 90Sr in the course of laboratory longevity tests. The changes in the surface morphology of the copper foil at the detector cathode that have occurred as a result of action of an electron beam have been described. The quantitative estimate

Abstract Different models of hydrogen thermal desorption peaks have been analyzed. The model of volume-averaged concentration dynamics with a continuum parameter makes it possible to integrally take into consideration the dominance of limiting factors: diffusion and recombination of atoms into desorbing molecules. An analytical symmetry criterion for peaks versus the method of expanding a composed

Abstract Results of simulation, synthesis, and investigation of a double-resonance plasmon structure for excitation of different modes of surface plasmon–polaritons are presented. It is shown that a combination of the Kretschmann and Otto configurations on a single asymmetric multilayer structure can be used for excitation of the plasmon–polariton resonances. Parameters of such a structure are optimized

Abstract In the case of a severe accident at a nuclear power plant with light-water reactors, the most effective method for localization of the formed melt (corium) is its retention in the cooled reactor vessel whose integrity depends on the heat flux from the melt to the vessel. One of the critically important processes in this case is the oxidation of the melt by water vapor or air–vapor mixture

Abstract The gradient heat flux sensor made of a bismuth single crystal is calibrated. The volt–watt sensitivity of the sensor is determined and the method of data processing based on the 1D heat conduction equation for a thin plate is proposed. This method is tested on experimental data obtained for the initiation of a laser discharge in a calm atmosphere and in a supersonic gas flow.

Abstract A 2D problem of electromagnetic plane wave scattering by 1D-periodic structures with cylindrical elements of electromagnetic black hole type arranged on a semi-infinite substrate is considered. Two algorithms corresponding to the cases of E- and H-polarization are developed on the basis of the hybrid projection method with accounting for refractive index distributions in the black holes of

Abstract The evolution of a microsecond pulsed barrier discharge initiated in atmospheric pressure air in the point–plane electrode geometry has been investigated using streak camera photorecording and shadow photography with micrometer resolution and nanosecond exposure. It has been shown that the discharge develops in series and its structure evolves both within a series and from series to series

Abstract Sensitivity of sensors of aqueous solutions in which a terahertz signal is reflected from a structure consisting of a dielectric film and solution is studied. The maximum sensitivity is reached at angles of incidence and radiation frequencies that provide zero reflection of monochromatic radiation from the specified structure. Conditions for such reflection are determined for the s- and p-polarized

Abstract This review presents the author’s view on modern trends in the development of charged particle accelerators for various applications, which is based on his own experience in this research field. The most promising, in the author’s opinion, areas of application of resonance accelerators are shown, in which substantial progress has been made by using new technologies. The use of high-gradient

Abstract The dynamics of synthesis and accumulation of protoporphyrin IX induced by 5-aminolevulinic acid (5-ALA) was studied using confocal fluorescence microscopy in three established cell lines: immortalized cells originated from human tumor tissues—epithelial carcinoma (HeLa cells) and lung adenocarcinoma (A549 cells)—and immortalized fibroblast-like mouse embryo cells (3T3 line). The accumulation

Abstract The evolution of the crystal structure of (1 – x)PbFe2/3W1/3O3 – xPbTiO3 solid solutions depending on the PbTiO3 concentration (at x = 0.25, 0.3, and 0.35) near the morphotropic phase boundary has been investigated using X-ray diffraction at room temperature. It is established that all three compositions are mixtures of the cubic and tetragonal phases and that an increase in the PbTiO3 concentration

Abstract The influence of temperature (in the interval of 300–400 K) and concentrations on the electrical conductivity, thermal conductivity, and thermoelectric power of copper chalcogenide-based crystals with the general formula (GeSe)1 – x(CuAsSe2)x has been considered. Heat transfer mechanisms have been determined. It has been found that the temperature dependence of thermal conductivity is nonmonotonic

Abstract In this paper, the authors suggested a finite element approach to the simulation of mechanical properties of functionally graded materials (FGM) using a multilinear plastic material model. The approach was used to simulate tensile test experiments on the homogeneous specimens manufactured at two laser power regimes and composite specimens based on the materials considered. We showed a correlation

Abstract Using a thermodynamic approach, a disperse system formed by an ensemble of particles with various shapes and volumes is studied. The shape of a particle is set by the value of its fractal dimension, which characterizes the relationship between the volume and surface area. Using the methods of number theory and the Hardy–Ramanujan–Rademacher formula, the size distribution functions of the dispersed

Abstract A continuous wavelet transform is used to analyze operation of a nonstationary signal of a quantum frequency standard. A method of translation transfer is proposed for elimination of the boundary effects in such a transform. Spectral integrals of the signal of the quantum frequency standard are calculated in several frequency intervals. A wavelet variance is introduced to determine time moments

Abstract Nanopowders of two crystalline phases, magnesium–aluminum spinel (98 wt %), and cuprite (2 wt %) have been obtained by laser evaporation of a solid target, which is a mechanical mixture of simple oxides (MgO, Al2O3, CuO). These nanopowders have been used to prepare test samples of transparent Cu:MgAl2O4 ceramics, the IR transmission spectra of which revealed two new strong absorption bands

Abstract The results of testing the degradation of light-emitting diode structures with InGaN/GaN quantum wells are reported. An increase in the external quantum efficiency as compared to the initial value is observed after the passage of current of 150–170 mA. Possible physical processes leading to a change in the quantum efficiency and an increase in low-frequency noise are considered.

Abstract A neutron source composed of a tandem accelerator with vacuum insulation and a lithium target is used to develop the boron neutron capture therapy and other applications. The dependence of the proton beam size on the target surface on the beam current is measured with thermocouples inserted inside the target and with a infrared camera. It is found that there is no appreciable influence of

Abstract We propose an original method for numerical calculation of heating of high-current electric contacts in the closed state by pulsed currents with a duration comparable with the period of the industrial-frequency current. Such regimes are typical of current-carrying systems of high-voltage electric facilities during switching high-power loads, during failure in electric transmission lines, and

Abstract The electrophysical properties and the resistive switching effect in ITO/SiNx/Si memristor structures have been investigated. A silicon nitride film ~200 nm thick with a Si/N ratio varying with depth has been deposited on a silicon substrate by chemical vapor deposition. The current–voltage characteristics of ITO/SiNx/Si-p structures have shown that the conduction mechanism in a high-resistivity

Abstract Experimental results on measuring the resonance frequency ratio of the protons of water and of 23Na nuclei in NaCl solutions with concentrations from 0.1 to 0.5 g per 100 g H2O are presented. Signals of water protons and sodium nuclei were acquired simultaneously, which allowed minimizing random and systematic uncertainties in measurements of the ratio of resonance frequencies f(H2O)/f(23Na+)

Abstract Hydrogenized carbon films 0.5–7.0 μm thick doped with silicon (11.9 ± 0.4 at %) and oxygen (1.7 ± 0.1 at %) have been grown on VT-6 titanium and silicon substrates in an externally heated arc discharge plasma. The hardness, internal stresses, surface morphology, wettability, and surface potential of the films against their thickness have been studied. It has been found that as the film gets

Abstract The dielectric properties of polycrystalline fullerite films with a thickness of ~300 nm included in p-Si/C60/InGa structures under dc electric fields with a strength up to 3.3 × 107 V/m have been investigated in the frequency range of 30–106 Hz. It is established that, at negative polarity of an InGa electrode (when electron injection from the metal to fullerite is facilitated), an anomalous

Abstract The Fourier law correctly describes heat transport in most practical macroscopic problems. However, for heat transfer in rapid processes, heat transport on micro- and nanoscales, and heat transfer in materials with an internal structure (porous media and biological tissues), other models are required that take into account nonlinear effects, as well as temporal (memory) and spatial nonlocality

Abstract Excitation of electromagnetic field at ultralow, extremely low, and lower frequencies by a horizontal grounded antenna in a two-layer medium is considered. Approximate analytical formulas are derived to describe field evolution in the low-frequency range. Accuracy of the quasi-stationary approximation is analyzed. Substitution of the impedance of a plane wave that is normally incident on the

Abstract The possibilities of using medium-energy (hundreds of kiloelectronvolts) ion beams for diagnostics of solids by measuring the spectra of characteristic X-ray radiation are considered. A modification of the method is proposed that consists in using probing beams of neutral atoms. It is shown that the use of such beams makes it possible to eliminate the negative effect of the surface potential

Abstract This paper presents the results of simulation of the collector of a prototype gyrotron designed for the DEMO project. Trajectory analysis in a collector with four-stage recovery of the residual beam energy based on the method of spatial separation of electrons in crossed azimuthal magnetic and axial electric fields was carried out. In this part of the research, the azimuthal magnetic field

Abstract It is shown that application of B2O3 as a flux allows one to obtain nominally pure composition-homogeneous LiNbO3 crystals characterized by high, close-to-stoichiometry ordering of structural units of the cation sublattice and high resistance to laser radiation. It have been established by calculations that boron can be incorporated into faces of oxygen tetrahedra of the LiNbO3 crystal structure

Abstract We have investigated experimentally the reflection of an electromagnetic (EM) wave in the microwave range at a frequency of 10.65 GHz from a layer of a magnetic fluid (magnetic colloid) and composites synthesized on its basis. It is found that, upon an increase in the solid-phase concentration, the conditions for the emergence of ferromagnetic resonance in the homogeneous magnetic colloid